The positive influence of intravenously feeding fluids to a patient over prescribed periods of time have been recognized by the medical profession. Further, while in a conventional sense glucose or the like is intravenously fed to a patient through a cannula assembly, many arrangements have heretofore been suggested and employed where a plurality of fluids are intravenously fed to a patient, either simultaneously or in a prescribed sequential fashion.
In the development of the multiple feeding systems, arrangements have been provided whereby a plurality of containers have been connected to a single cannula assembly via a wye connection or the like. Conventionally, this has been referred to as a piggy back arrangement, where one of the bags may be suspended at an elevation greater than the other. In certain arrangements where multiple fluids are administered to a patient, one of the fluids constitutes medication where the medicine has been premixed with distilled water, saline solution or the like, while the other fluid is a conventional I.V. fluid such as a saline solution, glucose or the like. In utilizing these systems, the medication fluid is administered at a particular rate in accordance with the requirements of medical personnel. Since the unit, when used, is normally employed over protracted periods of time for a single patient after which it is discarded, it is quite beneficial that the system remain viable for periodic administration of medication. Normally therefore, with knowledge of the volume of medication fluid to be administered and the rate of administration, a nurse can calculate the time required for administration of the medication, and return to the patient' s room at the appropriate time to switch flow from the medication leg of the wye to flow of I.V. fluid which precludes the introduction of air into the system and also very importantly precludes clotting of blood and therefore blockage in and around the cannula assembly which would necessitate the use of a new assembly that must again be inserted into the patient's vein, which of course is both costly and cause discomfort to the patient.
A primary concern in the normal arrangement, if not the most important concern, is the requirement that medical personnel be in attendance to switch over from administration of medication to the I.V. fluid. Not only is the arrangement problematical due to human error or forgetfulness, but the arrangement also intensifies the need for additional medical personnel proximate to where the fluids are being administered, and often presents problems where nurses or other medical personnel are needed at more than one location at the same time.
A great deal of development effort has been expended in the area of improving the system described above by way of the use of audible alarms to indicate cessation of medication or I.V. flow; the use of positive driven pumps to control the rate of fluid flow through the system; the use of certain switching arrangements where pressure variation in the system would automatically cause valves to open or close and the like, all of which are directed to reducing the time required by medical personnel in administering the medication and switching to the I.V. fluid, while not detracting from patient comfort, or increasing the probability of air entering the system or clotting of the infusion assembly. Certain prior art patents are directed to arrangements for improving the intravenous feeding apparatus as exemplified by U.S. Pat. No. 2,999,499; 3,216,419; 3,521,635; 3,543,752; 3,756,237; 3,776,229; 3,886,937; 3,929,157; 3,931,818; 3,967,620; 3,982,534; 4,000,738; 4,010,750; 4,037,596; 4,056,333; 4,096,879; 4,099,527; 4,103,686; 4,137,915; and 4,146,028.
The apparatus and method of the present invention represents an improvement over systems heretofore devised, in that, the present system provides automatic switch over upon cessation of a first fluid flow to a second fluid flow without presence of a nurse or other attendant in virtually a fail safe fashion. The known prior art as set forth above is not believed to either anticipate or suggest the apparatus or method of the present invention.